THE OPHIURIDiE. 



165 



many small scales. Outside the radial shields there is a narrow band of verj 

 small scales. Under side of the disk covered by small, overlapping scales, 

 which are somewhat projecting, giving the under side a rather curious 

 aspect. Several larger plates are seen among the small ones, besides a row 

 of larger scales along the margin. Genital scale distinct in the whole length, 

 the inner end covered by small, overlapping scales. The margin has a little 

 median cut in each interbrachial space ; the edge of the disk is rather sharp. 

 Three, on the inner joints four, rather thick, a little curved arm-spines; 

 about as long as one joint and a half or two joints. Sometimes they are 

 equal, sometimes the upper one is a little longer. Two large, oval tentacle 

 scales, that on the outer side the larger, more or less covering that on the 

 inner side, which is inserted on the ventral plate. 



Color in alcohol : dark gray. 



Stations 3354, 322 f. ; 3356, 546 £; and 3394, 511 f.; one specimen 

 from each station. That from Station 335G is very large (diameter of disk, 

 27 mm.), bat badly preserved. The spines are more flat, especially the 

 lower one on the joints enclosed in the disk. The arm is higher and 



4 



the dorsal plates are broader than in the specimen described. On the inner 

 free joints the upper arm-spine is as long as two joints and a half. The 

 marginal plates are not distinct. The scales of the under side are so small 

 that it appears almost naked. The same is the case in the third specimen. 

 In these two specimens the side mouth shields meet within, and are equally 

 broad in their whole length. 



OPHIACANTHA. 



In this genus the spines of the disk" are of no little systematic importance. 

 Lymak distinguishes grains, spines, stumps or crotchets ; as there are, how- 

 ever, transitional forms (e.g. "grain-like stumps"), it is often difficult to 

 determine to which of these sorts the spines, etc. in specimens under exami- 

 nation belong. This difficulty is easily overcome when the spines, etc. of 

 every species are figured. This we have done here with our species, and it 

 should be done in the future by every one who may describe species of 

 OpMacantha, Also those of the species already known should be figured, if 



there is occasion. 



10 



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